(1) Field of Use: Wherever there is a need for a display board having quickly replaceable display characters.
(2) Prior Art: The following patents are known to exist in this or related fields:
U.S. Pat. No. 1,879,002, was issued to C. C. Alles on Sept. 27, 1932, for a Movable Magnetic Marker arrangement for use in visibly displaying musical notes and symbols on a sheet of continuous iron cross-section containing a musical staff and scale illustration thereon.
U.S. Pat. No. 2,600,505 was issued to M. H. Jones on June 17, 1952, for a Layout Board for Photographic Reproduction, which employs several vertically extending channels of back to back multiple horseshoe bar magnets overlaid by an adhesive backed paper that provides a mounting base for want-ads printed on the top side of a paper having an iron dust coating on the back side.
U.S. Pat. No. 2,825,160 was granted to A. R. Mellor on Mar. 4, 1958, for a Menu Holder and Magnetic Support Means Therefor. This patent discloses a magnetic arrangement for holding an entire menu folder.
U.S. Pat. No. 3,093,919 issued to H. J. Holtz on June 18, 1963, for a Magnetic Display Arrangement, that comprises a non-magnetic layer having an adhesive backing engaging a magnet of the same size for a visible game board. The game pieces are non-magnetic with a magnetizable bottom layer of varnish and powdered iron, or alternately, an iron foil.
U.S. Pat. No. 3,122,684 granted on Feb. 25, 1964, to R. I. Genin, for Magnetized Game Board Configurations. This patent discloses a technique for making and hanging signs by implanting short length magnetic bar pieces (taken from a longer breakaway bar) into the back side of the characters to be displayed.
U.S. Pat. No. 3,168,787 was issued to M. Surrey on Feb. 9, 1965, for a Display Board, that utilizes spaced apart magnet elements that engage grooves in a backing structure to magnetically support a plurality of individual panels that each hold their display items between cooperating lips in a non-magnetic retention.
U.S. Pat. No. 4,366,637 was granted Jan. 4, 1983 to D. V. Dechanmps for a Set of Advertising Components, namely characters of a magnetic rubber-like material having a film of anti-adhesive varnish on one side and a protective coat of vinyl on the other side to support a printed silk screen layer thereon. These characters will thus adher to a steel panel or filing notebook having steel sheets therein.